Semiconductor device having metal gate

Abstract

A semiconductor device having metal gate includes a first metal gate structure and a second metal gate structure disposed in a first device region and in a second device region on a substrate respectively. The first metal gate structure includes a gate insulating layer, a first bottom barrier layer, a top barrier layer, and a metal layer disposed on the substrate in order, wherein the top barrier layer is directly in contact with the first bottom barrier layer. The second metal gate structure includes the gate insulating layer, a second bottom barrier layer, the top barrier layer, and the metal layer on the substrate in order, wherein the top barrier layer is directly in contact with the second bottom barrier layer. The first bottom barrier layer and the second bottom barrier layer have different impurity compositions.

What is claimed is: 
     
       1. A semiconductor device having metal gate, comprising:
 a substrate; 
 a first metal gate structure, disposed in a first device region on the substrate, the first metal gate structure comprising:
 a gate insulating layer and a first bottom barrier layer disposed on the substrate in order; 
 a top barrier layer, disposed on a surface of the first bottom barrier layer and directly in contact with the first bottom barrier layer; and 
 a metal layer, disposed on the top barrier layer; and 
 
 a second metal gate structure, disposed in a second device region on the substrate, the second metal gate structure comprising:
 the gate insulating layer and a second bottom barrier layer on the substrate in order, wherein the first bottom barrier layer and the second bottom barrier layer have different impurity compositions; 
 the top barrier layer, disposed on the second bottom barrier layer and directly in contact with the second bottom barrier layer; and 
 the metal layer disposed on the top barrier layer. 
 
 
     
     
       2. The semiconductor device having metal gate according to  claim 1 , wherein the first bottom barrier layer and the second bottom barrier layer include different contents of aluminum atom. 
     
     
       3. The semiconductor device having metal gate according to  claim 1 , wherein the first bottom barrier layer and the second bottom barrier layer have different concentration gradients of aluminum atom. 
     
     
       4. The semiconductor device having metal gate according to  claim 1 , wherein the first bottom barrier layer and the second bottom barrier are respectively a multi-layer structure. 
     
     
       5. The semiconductor device having metal gate according to  claim 4 , wherein each of the multi-layer structures is a TiN/TaN stacking layer and the top barrier layer is a titanium nitride layer. 
     
     
       6. The semiconductor device having metal gate according to  claim 1 , wherein the first metal gate structure is a P-type metal gate of a P-type transistor, the second metal gate structure is an N-type metal gate of an N-type transistor, and a content of aluminum atom of the first bottom barrier layer is less than a content of aluminum atom of the second bottom barrier layer.